Machines for plucking the feathers from poultry are used in poultry processing plants. These plucking (or picking) machines typically have drums and/or discs to which resilient rubber or similar material picking fingers are mounted. The drums or discs are positioned along each side of a path of travel along which birds are conveyed. The drums or discs are rotated at speeds as high as 600 to 1250 rpm causing the resilient fingers to be continuously driven into contact with the birds. Frictional forces between the rubber fingers and the feathers remove the feathers from the bird. However, the fingers tend to wear quickly, with an average processing line requiring replacement of from 8,000 to 10,000 fingers per month. With many processing plants running several processing lines, it is common for a plant to replace one half million fingers per year.
Picker fingers typically have an enlarged disc-shaped base formed with an annular recess from which a tapered, furrowed shank extends. Each finger is individually installed in a disc with the annular recess of the finger base located within a hole in the support disc or drum, with the recess edges abutting and gripping opposite sides of the rim about the hole of the support disc. Worn fingers are often removed from the disc by cutting the finger at its annular recess. The two pieces can then be removed. A new finger is installed by insertion through the enlarged hole in the disc until its tapered surface adjacent its enlarged base engages the rim about the hole. The shank is then pulled with a substantial degree of force in order to seat the annular recess about the edge of the hole. It is difficult to seat the picking fingers within the disc holes manually due to the amount of force required in pulling their base portions into the support holes. Further, the region of the disc and the attached fingers becomes dirty and “gummy” from the fat from the birds and dust from the feathers, A substantial amount of strength is required to seat replacement fingers, and the space available in which to work is usually quite restricted making it awkward to exert the force needed to properly seat the annular recess about the hole edge. Also, substantial training of the personnel doing the finger replacement is required. A prior art mechanism utilized individual fingers mounted to extend through mating holes in a support plate, and having a backing plate abutting the rear of the support plate to hold each finger securely. To ensure that the backing plate and the support plate rotated as a unitary piece, an integrated centrifugal locking mechanism was utilized. This locking mechanism was required to hold the support plate and the backing plate together tightly when the disc assembly was rotating at its maximum velocity.
In addition, it should be noted that the finger locking mechanism becomes inoperable after a few hours due to gumming from the poultry fat and from debris and fat clogging the locking mechanism, and often fingers break off, requiring replacement for either reason.
A plucking machine typically has 64 discs of ten fingers each, and there are usually four machines in a plucking line. Wholesale changes of fingers are often required. To change the fingers on a single machine at the present time requires from 4 to 7 man hours per machine. It should also be noted that during finger changes, frequently some of the rubber fingers are accidentally dropped into a drain or an offal tray.